The subject invention relates to a heat dissipator used with dual in line integrated circuit packages. More specifically, a resilient, unitary heat dissipator is disclosed which may be readily mounted on an IC package for dissipating heat generated in the package while in operation.
The development of integrated circuits, wherein a plurality of interconnected circuits are contained in a single package, has enabled the miniaturization of a variety of devices. The configuration of the IC package has been generally standardized and consists of a longitudinally extending, rectangular housing having a number of flat leads extending downwardly from opposite sides of the package in two parallel rows. In the assembly of electrical devices, the leads of the IC package are connected to the electrical circuitry. In order to facilitate the replacement of the IC package, standardized IC sockets were developed which are soldered directly to the circuit, with the IC package being removably mounted in the socket.
In the operation of the device, heat is generated in the IC package which is proportional to the amount of current being driven therethrough. Since the IC packages are relatively small, and usually closely spaced on a printed circuit board, temperatures within the packages can increase 40.degree.-50.degree. centigrade, often causing problems to develop. For example, as the temperature of an IC package increases, its efficiency will decrease. More importantly, continuous high current levels driven through an IC package can result in the breakdown of the circuitry due to high internal temperatures.
Accordingly, in the prior art, a variety of heat dissipators or heat sinks have been developed for conducting and radiating the heat away from an IC package. One commonly used heat dissipator for use with IC packages consists of rectangular plate member having a plurality of upwardly extending radiating fins. The dimensions of the rectangular plate substantially conform to the dimensions of the top wall of the IC package and is adhesively connected thereto. By this arrangement, heat generated throughout the IC package is conducted through the plate, to the fins and radiated into the air.
While the latter heat sinks were capable of achieving some amount of temperature reduction, they have proved to be undesirable for a variety of reasons. For example, the requirement of adhesively connecting individual heat dissipators to each IC package is time consuming and expensive. Further, should it be desired to remove an IC package from the circuit, the replacement package must be provided with a new heat dissipator since the original dissipator cannot be reused. Another significant disadvantage of the top mounted heat sinks relates to the internal construction of a conventional IC package. More specifically, in a typical IC package, an integrated circuit chip is centrally located adjacent the bottom wall of the housing. Thus, in use, heat is initially generated adjacent the bottom wall. Accordingly, when utilizing the prior art dissipators, the heat must first travel through the housing towards the top wall by conduction, before it can be dissipated by a top mounted dissipator.
In order to overcome these shortcomings, various other prior art heat dissipators were developed. For example, a heat dissipator has been developed which includes separate top and bottom plate members. More specifically, a bottom plate member is provided which is fit around an IC socket prior to the mounting of the IC package. After the IC package is mounted over the bottom plate member, a top member is added and affixed to the bottom member. This prior art combination enables a portion of the heat generated by the integrated circuit chip to be conducted directly away from the bottom wall of the housing. The latter prior device however is undesirable in that it requires complex mounting and connection procedures. Further, to facilitate mounting and interconnection, flanges are provided which extend beyond the plan dimensions of the IC socket. The latter shortcoming is particularly undesirable where space requirements are critical, since additional distance must be provided between each IC socket to accommodate the projecting flanges.
Another example of a heat dissipator found in the prior art which enables a plurality of IC packages to be simultaneously cooled, includes a conductive metal plate member. More specifically, on a printed circuit board, wherein a plurality of IC packages are mounted in a planar array, a metal plate can be mounted such that the top wall of each housing is in contact therewith. By this arrangement, a single plate can conduct heat away from the tops of all the packages. The latter prior art dissipator obviates the necessity of adhesively connecting individual heat sinks to each IC package. However, as can be appreciated, the heat generated at the bottom of the package still must be conducted throughout the housing, to the top wall, before it can be removed by the plate.
Accordingly, it is an object of the subject invention to provide a new and improved heat dissipator for a dual in line integrated circuit package.
It is another object of the subject invention to provide a new and improved heat dissipator which may be slidably and removably mounted on an IC package.
It is a further object of the subject invention to provide a new and improved heat dissipator which is operative to directly remove the heat generated adjacent the bottom wall of the IC package housing.
It is still another object of the subject invention to provide a new and improved heat dissipator which is unitary in construction, and formed from a resilient material so that it may be easily mounted and removed for reuse.
It is still a further object of the subject invention to provide a new and improved heat dissipator which does not extend beyond the plan dimensions of a rectangular IC socket.
It is still another object of the subject invention to provide a new and improved heat dissipator which includes a means for inhibiting the relative movement between the dissipator and the IC package thereby preventing unwanted shifting due to vibration or other causes.
It is still a further object of the subject invention to provide a new and improved heat dissipator which may be used in combination with a heat dissipating plate to increase the amount of heat removed from the IC package.